Telephone-exchange system.



E. E. HiNRICHSEN & L. H. JOHNSON.

' TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED MAY 16, 191 6.

1 @38 l i 1 o Patented Aug. 28, 1917.

/n Ven fans: Edwa/ d E. H/l'IF/C/Lfif/Z LW/S H. Johnson.

UNITED STATES PATENT OFFTGE.

EDWARD n IE-IINRICH-SEN, or nasr ORANGE, AND LEWIS n. aonnson, or BLOOMFIELD,

NEH/V JERSEY, ASSIGNORS TO WESTERN ELECTRIC A CORPORATION OF NEW YORK.

COMPANY, OF NEW YORK, N. Y.,

TELEPHONE-EXCHANGE SYSTEM.

Application filed May 16, 1916.

To all 0507mm itmag concern Be it known that we, EDWARD E. HINRICH- SEN and Lnwrs H. JOHNSON, citizens .of the United States,-residing atEast Orange, in the county of Essex and State of New Jersey, and at Bloomfield, in the county of Essex and E'itate of New Jersey, respectively, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone can change systems, and more particularly to improvements in trunk or connecting circuits for service between remote telephone switching centers or between difierent telephone switchboards.

The principal object of this invention is to provide a trunk circuit for completing telephone connections between amagneto telephone system and a central-energy telephone system, on and iii-connection with which call signals, guard signals and disconnectsignals are adapted to be displayed automatically in synchronism with corresponding steps in the processes of establishing and handling connections thereover, the displayrandoperation of the signals being reciprocal with respect toeach end of the trunk circuit.

In accordance with this invention, circuit controlling devices, responsive automatically to connecting operations at each end of the trunk circuit, are adapted to interchangeably connect the .main conductors of the trunk circuit to permit grounded circuit working over one wire, simplex grounded working over both wires and loop circuit working over both wires. In synchronism with these line circuit changes, suitable electro-responsive devices are respectively affected by simple current action, accumulative compound current action and differentialcompound current action, all in a manner to display at the proper moment either a signal.

This invention is illustrated diagrammatically in the accompanying drawing, in which a link circuit suitable for completing connections between the telephones .of a magneto system is partially shown at a position A, and a link circuit for completing connections between the telephones of a centralenergy system is partially shown at a Specification of Letters Patent.

Patented A11 28, 1917.

Serial No. 97,766.

through which a connection progresses to completion and is finally disposed of will be .traced, and in order to clearlyset forth the features oflthis system, relative to the recip- .rocal operation of the signals, calls, assumed asbeing routed in different directions, will.

be described.

"In tracing a first call, let it be assumed that an operator at the terminal of the link circuit at position A, in answeringa subscriberat that point, receives a request for a connection with a subscriber whose line terminates .at the position of the link circuit of position B, which :may be located in a distant station or in another operators posi tion in the same station. A plug 1 is inserted ina jack 2, whereupon the contacts 3 .OEwtlllS jflCk complete a circuit which may be traced from the distant end of the, trunk circuit over a path formed .through the grounded battery, .the 1right-hand winding of a compound-wound relay 4:, the upper- ..most conductor of the trunk circuit, the

right-hand winding of a compound-wound signal 7 thenceto earth over the contacts 3 of .thejack2. This results in the operation of the relay t, the closing of whose contacts 6 causes .a call signal lamp 8 to be lighted,

and the electromagnetically operated signal 7 beingalsoenergized, serves at such time [as a guard signal. call signal, a guard signal or a disconnect ing a plug 9 into a 'jack 10. Battery current from the link circuit over the main conductors of this connection operates a relay ll. Separation of the contacts of the relay .11 removes ashort circuit normally present about the Winding of arelay 12, whereupon the latter relay is operated by a current from the sleeve conductor 7 of the link circuit terminating at position B. Separation of the contacts 13 of the relay 12 disables the contacts of the relay 11. The closing of the contacts 15 of the relay 12 furnishes a ground for the battery to cause the operation of a relay 16, and in turn, the separation of the contacts 17 of this relay disconnects the relay 11. On the closing of the contacts 18 of the relay 16, a relay 20 is operated by a circuit further completed from the battery through the contacts 6 of the relay 4:. Separation of the contacts 21 of the relay 2O disconnects the signal lamp 8, and the closing of the contacts 24 of this relay connects the main conductors of the trunk circuit to form a loop circuit which is further completed through the contacts 19 of the relay 16. The battery current supplied through the righthand winding of the relay 1 now divides and flows in approximately equal quantity over each conductor of the trunk circuit, thence completing circuit through the right and left-hand windings, respectively, of the signal 7' to earth through the contacts 3 of the jack 2. This current produces a differentialcompound etfect with respect to the windings of the signal 7, which is accordingly deenergized to efface its indication previously serving as a guard signal. A supervisory relay 26 of the link circuit, terminating at position B, is operated by battery current therefrom which completes circuit over the ring contacts of the plug 9, the jack 10, and a resistance unit 27, thence to earth over the contacts 5 and 6 of the relay 4. The relay 26, thereby operated, connects a resistance unit 28 in parallel with a supervisory lamp 29, thereby extinguishing the lamp.

By means of telephone sets (not shown), the operator at position A requests the operator at position B over the trunk circuit C to complete the connection to the line of the subscriber wanted. The operator at position B thereupon connects the opposite or calling end (not shown) of the link circuit terminating at position B to the line circuit of the subscriber wanted. It will be understood that the answering end (not shown) of the link circuit terminating at A is joined at that exchange to the line of the subscriber who originated the call.

During the time the link circuits terminating at positions A and B are joined to the trunk circuit C, the signals 7, 8 and 29 are effaced. Following the termination of the conversation between the connected subscribers, the operator at A removes the plug 1 from the jack 2 and the resulting separation of the contacts 3 of this jack opens the previously traced circuit for the relay 4. Separation of the contacts 5 and 6 of the relay 4 disconnects the supervisory relay 26 and, in turn, the separation of the contacts of the latter relay disconnects the shunting resistance 28 from around the lamp 29,

which is thereupon lighted to serve as a disconnect signal. The contacts 14; of the relay 12 being at this time connected in parallel with the contacts 6 of the relay t, the relay 20 continues energized over a circuit further 3 completed from the battery through its own contacts 22 and 28. Following the removal of the plug 9 from the jack 10, in response to the presence of the disconnect indication on the lamp 29, the relays 12, 16 and 20 are disconnected, thereby completely restoring the trunk circuit to its normal condition.

In tracing a call routed in a direction opposite to that of the call just described, let it be assumed that the operator at position B has answered a subscriber at that point and received a request for a connection with a subscriber whose line terminates on the switchboard which is assumed to be located at position A.

The operator at B, in this case the originating operator, inserts the plug 9 into the jack 10, whereupon battery current from the link circuit traverses the main conductors of this connection to operate the relay 1]. as before. The operation of the relay 11 permits the operation of the relay 12, which, in turn, effects the operation of the relay 16 as already described, and the closing of the contacts 19 of this relay completes a signaling loop formed through the main conductors of the trunk circuit. This loop circuit may be traced through the battery, the righth aud winding of the relay 4, the uppermost trunk conductor, serially through both windings of the signal 7, the lowermost trunk conductor, the contacts 19 of the relay 16, contacts 25 of the relay 20, thence to earth through the left-hand winding of the relay 4. Under this current action, the relay 4 remains inert, due to the differentialcompound etlect present in its windings. In response to this call signal, manifested on the signal 7, due to the accumulative compound etfect ot the current action in its windings, the operator at A answers by in sorting the plug 1 into the jack 2. The resulting closing of the contacts 3 of this jack shunts that portion of the loop circuit formed by the left-hand winding of the signal 7, the lowermost trunk conductor, and the left-hand winding of the relay 4:. The resulting cessation of current through this portion of the previously traced circuit removes the neutralizating etl ect in the relay 4:, which is thereupon operated through its right-hand winding over the circuit completed through the uppermost trunk conductor, the right-hand winding of the signal 7 to the earth connection through the contacts 3 of the jack 2. Following" the closing of the contacts 5 and 6 of the relay 4, the relay 20 is operated over the path further completed through the contacts 18 of the relay 16. The contacts 24 of the relay 20 130 viously described operating circuit of the supervisory Lrelay 26, the contacts of which connect the shunting resistance unit 28 to extinguish the lamp signal The completed'ta'lking loop of the trunk conductors permits the current supplied through the rigl'it-hand winding of the relay 4: to complete circuit in parallel through the windings of the signal '7, to earth through the contacts of the jack 2. The windings being associated differentially when connected in parallel, the neutralizing of the current effects in the windings of the signal 7 causes this signal to be restored. The circuits being now established in the talking position, the signals 7, 8 and 29 are effaced, as before. On the conclusion of the conversation between the two subscribers thus connected, the operator at B removesthe plug 9 from the jack 10, thereby releasingthe relays 12 and 16. Separation of the contacts 19 of the relay 16 disconnects the talking loop of the :trunk circuit, thereby causing cessation of battery current through the left-hand WlIlCl ing of the signal 7, thus eliminating the neutralizing effect of the currents in this signal, whereupon the signal responds to the simple current action present in its right-hand winding. The relay 4 is retained operated through supplying the current to the signal '7. as described, and, in turn, retains the relay 2O energized to prevent the lighting of the lamp 8 at this time. The contacts 22 of the relay 20 are connected in parallel with the contacts 18 of the relay 16 through which the relay 20 is initially operated, therefore, the latter relay continues selflocked under control of the contacts 6 of the relay 4. On the display of the signal 7, which, in this case, is a disconnect indication, the operator at A removes the plug 1 from the jack 2, and the resulting separation of the contacts 3 of this jack completes the restoring of the trunk circuit apparatus to its normal position.

The purpose of the relay 11 is to serve as a means for disconnecting or tripping socalled automatic or machine ringing devices (not shown) employed for automatically disconnecting ringing current, and for connecting the circuits in a talking position. Such devices may be employed with the link circuits at position B for service on other lines than the trunk circuit shown. A generator 30 for supplying ringing current to the link circuit at position A is only required for service on other connections on which the link circuit may be used, but is not required for service on the trunk circuit.

In supplying current to the trunk circuit and to -the link circuit at position ;B,'several batteries have for convenience been shown in thedrawing. It will be-understood, however, that thesebatteries may be, and preferably are, one and the same battery.

It will be understood that repeating coils indicated at 31 and 32 are for the purpose of dividing the trunk circuit into an intermediate or main line section and two ter- -minal sections, one at each end thereof.

Telephonic or voice currents are repeated through-these'coils which serve to prevent the battery current from the trunk circuit reaching the link circuits at the magneto switchboard, and to isolate the battery circuits of the link conductors at the common- "batteryswitchboard from the conductors of the intermediate or main trunk section.

What is claimed is: '1. In a telephone trunk circuit, a signal :arida compound-wound signal-control electroniagnet at each end thereof, means at each end of said circuit for establishing connections therewith, source of current, and switching means operated by said connectingineans for including said source of current with the windings of said electromagnets in different combinations to con- -trol the operation of said signals.

2. *In a telephone trunk circuit, a signal and a compound-wound signal-control electromagnet at each end thereof, a source of current, switching -means at each end of said circuit for establishing connections therewith, and circuit controlling means operated on the inclusion of a connection with one end of said circuit for connecting said source of current with said electromagnets to display said signals.

8. In a-telephone trunk circuit, a signal and a compound-wound signal-control electromagnet at each end thereof, a source of current, switching means at each end of said circuit for establishing connections therewith, circuit controlling means operated on theinclusion of a connection with one end of said circuit for connecting said source of current with said electromagnets to display said signals, and electro-responsive switching devices operated on the following inclusion of a connection with the other end of said circuit for including said source of current further with one of said electromagnets and with said electro-responsive devices to efi'ace said signals.

4. In a telephone trunk circuit, a signal and a plurality of relays including a compound-wound relay at one end thereof, a compoundwound electromagnetic signal at the other end of said trunk, a source of current, a link circuit at each end of said trunk, connection receiving means for each end of said trunk to receive said link circuits, a signal and a signal control relay for the link circuit at the relay-equipped end of the trunk, and switching means operated by said link circuit connections for including said source of current to set up current action in the relays and in the electromagnetic signal to control the operation of said signals.

5. In a telephone trunk circuit, a signal and a plurality of relays including a compound-wound relay at one end thereof, a compound-wound electromagnetic signal at the other end of said trunk, connection-receiving means for each end of said trunk, link circuits at each end of said trunk circuit adapted to be connected therewith, a signal for the link circuit at the relayequippcd end of said trunk and a source of unidirectional current at the same end of the trunk, and switching means controlled by the inclusion of the signal-equipped link circuit with said trunk to set up relay action to connect said source of current through each winding of said compound-wound relay and said electromagnetic signal to display said link circuit signal and said electromagnetic signal.

6. In a telephone trunk circuit, a signal and a plurality of relays including a com pound-wound relay at one end thereof, a compound-wound electromagnetic signal at the other end of said trunk, connection-receiving means r'or each end of said trunk, link circuits at each end of said trunk adapted to be connected therewith, a signal and a signalcontrol relay for the link circuit at the relay-equipped end of said trunk, a source of unidirectional current at the last-mentioned end of the trunk, and switching means responsive when the link circuits are included with each end of said trunk for connecting said source of current to set Copies of this patent may be obtained for five cents each, by addressing the Washington. D. 0.

up current action in said relays and said electromagnetic signal to prevent the display of said signals.

7. In a telephone trunk circuit, a signal and a signal-control electromagnet at each end thereof, means at each end of said circuit for establishing connections therewith, a source or current, and switching means operated by said connecting means for including said source of current in series with one winding of each electromagnet to display said signals.

8. In a telephone trunk circuit, a signal and a signal-control electromagnet at each end thereof, means at each end of said circuit for establishing connections therewith, a source of current, and switching means operated by said connecting means for including said source of current in series with one winding of one of said electromagnets and with both windings of the other of said electromagnets arranged in parallel to efiace said signals.

9. In a telephone trunk circuit, a signal and a compound-wound signal-control electromagnet at each end thereof, means at each end of said circuit for establishing connections therewith, a source of current, and means responsive to the operation of said connecting means to connect the windings of one of said electromagnets in differential relation and to connect the windings of the other electromagnet in compound relation with respect to said source of current, to control said signals.

In Witness whereof, we hereunto subscribe our names this 12th day of May, A. I). 1916.

EDl VARD E. HINRICHSEN. LEWIS H. JOHNSON.

Commissioner of Patents. 

